Tubular back beam assembly for vehicle and method of manufacturing the same

ABSTRACT

Disclosed are a tubular back beam assembly for a vehicle and a method of manufacturing the tubular back beam assembly. The tubular back beam assembly may include a plurality of main members, each of which is formed by cold rolling and hot stamping. The plurality of main members may be coupled to form a vertically stacked structure with flat portions coupled in a surface contact fashion. Or the tubular back beam assembly may include a main member and at least one support member that are directly coupled to form a vertically stacked structure.

CROSS-REFERENCE(S) TO RELATED APPLICATION

The present application claims priority of Korean Patent ApplicationNumber 10-2013-0129621 filed on Oct. 29, 2013, the entire contents ofwhich application are incorporated herein for all purposes by thisreference.

BACKGROUND OF INVENTION

1. Field of Invention

The present invention relates, in general, to a tubular back beamassembly for a vehicle and a method of manufacturing the same, and, moreparticularly, to a tubular back beam assembly for a vehicle, in which aplurality of tubular back beams are coupled in a vertically stackedstructure in a surface contact fashion, and a method of manufacturingthe same.

2. Description of Related Art

To protect a vehicle body and a passenger in the event of a collision, aback beam assembly is mounted in the front and rear of the vehicle.

FIG. 1 illustrates an example of a tubular back beam assembly. Aconventional tubular back beam assembly 1 has a structure in which anupper beam 1 a and a lower beam 1 b which have a circular cross sectionare installed at an interval in a vertical direction, intermediateportions of the upper beam 1 a and the lower beam 1 b are coupled usinga coupling bracket 1 c, and stays 3 or crash boxes used to couple toside members 2 are coupled to both ends of the upper beam 1 a and thelower beam 1 b.

The tubular back beam assembly 1 configured as described above has theeffect reducing weight and cost compared to a general integrated backbeam. In particular, each of the upper beam 1 a and the lower beam 1 bcan dissipate and absorb collision energy. Thereby, there is anadvantage in that collision performance can be more effectivelysatisfied.

However, the conventional tubular back beam assembly 1 as describedabove has a structure in which the upper beam 1 a and the lower beam 1 bare separated from each other, and the upper beam 1 a and the lower beam1 b which are separated from each other are coupled by the couplingbracket 1 c. Thus, in the conventional tubular back beam assembly 1,coupling strength of the upper beam 1 a and the lower beam 1 b isinsufficient. There is a high probability of the upper beam 1 a and thelower beam 1 b being vertically widened by collision energy in the eventof the collision of the vehicle. In this case, the conventional tubularback beam assembly 1 cannot effectively cope with the collision. Thus,the vehicle body suffers heavy damage, and the passenger may be greatlyinjured.

In addition, the upper beam 1 a and the lower beam 1 b of theconventional tubular back beam assembly 1 are manufactured by pressingor extruding a general steel pipe. The upper beam 1 a and the lower beam1 b manufactured as described above have a disadvantage in that they areheavy due to a thick construction and, in particular, it is difficult tosatisfy sufficient collision performance due to weak strength.

The information disclosed in this Background section is only forenhancement of understanding of the general background of the inventionand should not be taken as an acknowledgement or any form of suggestionthat this information forms the prior art already known to a personskilled in the art.

SUMMARY OF INVENTION

Accordingly, the present invention has been made keeping in mind theabove problems occurring in the related art and/or other problems, andthe present invention is intended to provide a tubular back beamassembly for a vehicle in which a plurality of tubular back beams arecoupled to form a vertically stacked structure in a surface contactfashion, and thereby, coupling strength and bending rigidity can beremarkably increased through the vertical stacked structure and thesurface contact fashion, and sufficient collision strength can besecured to further improve the capability of protecting a vehicle bodyand a passenger.

In addition, the present invention is intended to use a steel pipe whosethickness is reduced to reduce weight and increase rigidity by coldrolling and hot stamping as a material for a tubular back beam assembly.

Various aspects of the present invention provide for a tubular back beamassembly for a vehicle, which includes a plurality of main back beams,each of which is formed in a tubular shape and includes at least oneflat portion, wherein the plurality of the main back beams are coupledto form a vertically stacked structure with the flat portions ofadjacent main back beams coupled in a surface contact fashion.

Here, the tubular back beam assembly may further include: a pair ofcrash boxes whose front ends are coupled to rear surfaces of the mainback beams at both ends of the main back beams and whose rear ends arecoupled to members of a vehicle body, wherein vertical faces of thefront ends of the crash boxes are coupled to each of the plurality ofthe main back beams.

Further, the tubular back beam assembly may include a towing hook, oneend of which is detachably coupled to at least one of the main backbeams to which the crash boxes are coupled. One or each of the pluralityof main back beams may be formed to have substantially a quadrangularcross section to secure rigidity. The flat portions of the adjacent mainback beams are coupled to each other by welding.

According to another aspect of the present invention, there is provideda tubular back beam assembly for a vehicle, which includes: a supportback beam which is formed to have a C-shaped cross section with anopening extended in a longitudinal direction, and a main back beam whichis formed in a tubular shape having substantially a quadrangular crosssection and one portion of which is inserted into the opening of thesupport back beam to close the opening of the support back beam and forma vertically stacked structure along with the support back beam.

Here, the main back beam and the support back beam may be coupled sothat only one of an upper portion or a lower portion of the main backbeam is inserted into the opening of the support back beam.

Further, the tubular back beam assembly may include a pair of thesupport back beams, one disposed on the main back beam and one disposedunder the main back beam, and the main back beam and the support backbeams are coupled so that the upper and lower portions of the main backbeam are inserted into the openings of the support back beams.

According to yet another aspect of the present invention, there isprovided a method of manufacturing a tubular back beam assembly for avehicle, which includes: cold rolling and hot stamping a tubularcarbonous material to form at least two main back beams, each includingat least one flat portion extended in a longitudinal direction, andcoupling the at least two main back beams to form a vertically stackedstructure with the flat portions of adjacent main back beams coupled ina surface contact fashion.

Here, one or each of the at least two main back beams may be formed tohave substantially a quadrangular cross section to secure rigidity.Further, the flat portions of the adjacent tubular back beams may becoupled in the surface contact fashion by arc welding.

According to still another aspect of the present invention, there isprovided a method of manufacturing a tubular back beam assembly for avehicle, which includes: cold rolling and hot stamping a carbonousmaterial to form at least one support back beam having a C-shaped crosssection with an opening extended in a longitudinal direction, coldrolling and hot stamping a tubular carbonous material to form at leastone main back beam having substantially a quadrangular cross section,and coupling the at least one support back beam and the at least onemain back beam to form a vertically stacked structure.

Here, the coupling of the support back beam and the main back beam mayinclude inserting one portion of the main back beam into the opening ofthe support back beam, and coupling both ends of the support back beamand an overlapping portion of the main back beam by arc welding.

Further, the at least one support back beam and the at least one mainback beam may be coupled in a stacked way. In addition, the at least onesupport back beam may include two support back beams which are disposedon and under the main back beam and coupled with the main back beam in astacked way.

According to the present invention, main members, or the main member andat least one support member which are formed by cold rolling and hotstamping are directly coupled in a vertically stacked way, or coupled ina vertically stacked way with flat portions thereof coupled in a surfacecontact fashion. Thereby, there is an effect in which rigidity of themanufactured tubular back beam assembly can be remarkably increased, andsufficient collision strength can be secured. The capability ofprotecting a vehicle body and a passenger can be further increased, andthe tubular back beam assembly can be reduced in weight.

The methods and apparatuses of the present invention have other featuresand advantages which will be apparent from or are set forth in moredetail in the accompanying drawings, which are incorporated herein, andthe following Detailed Description, which together serve to explaincertain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view for describing a conventional tubular back beamassembly for a vehicle.

FIG. 2 is a perspective view of an exemplary tubular back beam assemblyfor a vehicle according to the present invention.

FIG. 3 is a cross-sectional view taken along line I-I of the tubularback beam assembly of FIG. 2 according to the present invention.

FIG. 4 is a cross-sectional view showing variations from that of FIG. 3.

FIG. 5 and FIG. 6 are cross-sectional views of another exemplary tubularback beam assembly according to the present invention.

FIG. 7 and FIG. 8 are views for describing exemplary methods ofmanufacturing a tubular back beam assembly according to the presentinvention.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of thepresent invention(s), examples of which are illustrated in theaccompanying drawings and described below. While the invention(s) willbe described in conjunction with exemplary embodiments, it will beunderstood that present description is not intended to limit theinvention(s) to those exemplary embodiments. On the contrary, theinvention(s) is/are intended to cover not only the exemplaryembodiments, but also various alternatives, modifications, equivalentsand other embodiments, which may be included within the spirit and scopeof the invention as defined by the appended claims.

As shown in FIGS. 2 to 4, a tubular back beam assembly 10 for a vehicleaccording to various embodiments of the present invention includes aplurality of main back beams 11, each of which is formed in a tubularshape and includes at least one flat portion 11 a. The main back beams11 are coupled in a vertically stacked structure with the flat portions11 a coupled in a surface contact fashion.

In other words, the tubular back beam assembly 10 according to thepresent invention has a structure in which the plurality of main backbeams 11 which are formed to have a quadrangular cross section orsubstantially a quadrangular cross section are vertically stacked withthe flat portions 11 a coupled in the surface contact fashion, and theflat portions 11 a are integrally coupled to each other such as by arcwelding.

Here, the main back beams 11 are formed in the quadrangular crosssection so as to be able to secure sufficient coupling strength. Withthis structure, there is an advantage in that the capability ofprotecting a vehicle body and a passenger can be further improved.

For example, the main back beams 11 may be formed of a tubular beamhaving a true circle cross-sectional structure. However, since the truecircle cross-sectional structure has a disadvantage in that it isvulnerable to deformation compared to a quadrangle cross-sectionalstructure. For this reason, the main back beams 11 of the presentinvention employ the quadrangle cross-sectional structure rather thanthe true circle cross-sectional structure as a basic cross-sectionalstructure so as to be able to secure excellent rigidity.

When the flat portions 11 a of the main back beams 11 formed to have thequadrangular cross section are coupled in a surface contact fashion, anintermediate widthwise cross-sectional thickness T1 is increased.Thereby, bending rigidity of the tubular back beam assembly 10 can beremarkably increased, and thus collision performance can be improved.

In addition, as in various embodiments of the present invention, whenthe plurality of main back beams 11 are coupled in the verticallystacked structure in the surface contact fashion, the conventionaldisadvantage that the main back beams 11 are vertically widened in theevent of the collision of the vehicle can be removed. Thus, thecapability of protecting the vehicle body and the passenger can befurther improved.

The tubular back beam assembly 10 for a vehicle according to variousembodiments of the present invention may have a structure in which thetwo main back beams 11 are coupled in a vertically stacked structure inthe surface contact fashion as shown in FIG. 3 or the three main backbeams 11 are coupled in the vertically stacked structure in a surfacecontact fashion as shown in FIG. 4 if necessary.

The structure of FIG. 4 may be relatively heavier compared to thestructure of FIG. 3, but its capability of protecting the vehicle bodyand the passenger can be further improved due to relatively improvedcoupling strength. Thus, the structure of FIG. 4 is suitable forvehicles that mainly place an emphasis on safety.

On the other hand, the tubular back beam assembly 10 according to thepresent invention further includes a pair of crash boxes 12 whose frontends are coupled to rear surfaces of both ends of the main back beams 11and whose rear ends are coupled to members of the vehicle body, and inwhich vertical faces of the front ends are entirely coupled to theplurality of main back beams 11 which are coupled in the verticallystacked structure.

As described above, when the crash boxes 12 are coupled to all the mainback beams 11 which are coupled in the vertically stacked structure,coupling strength of the crash boxes 12 can be remarkably improved andthus shock absorbing performance can be still further improved.

In addition, the tubular back beam assembly 10 for a vehicle accordingto various embodiments of the present invention further includes atowing hook 13, one end of which is detachably coupled to at least oneof the main back beams 11 to which the crash boxes 12 are coupled, andthus the towing hook 13 coupled as described above can have a morestable coupling force.

As shown in FIGS. 5 and 6, a tubular back beam assembly 10 for a vehicleaccording to various other embodiments of the present invention includesat least one support back beam 14 which is formed to have a C-shapedcross section in which one side thereof is opened in a longitudinaldirection, and a main back beam 11 which is formed in a tubular shape ofa quadrangular cross section and one portion of which is inserted intoan opening of the support back beam 14 so as to close the opening of thesupport back beam 14 and form a vertically stacked structure along withthe support back beam 14.

In other words, the tubular back beam assembly 10 has a structure inwhich the main back beam 11 formed to have the quadrangular crosssection and the support back beam 14 formed to have the C-shaped crosssection in which one side thereof is opened are vertically stacked andintegrally coupled to each other by arc welding.

In comparison with the structures of FIGS. 3 and 4, the structures ofFIGS. 5 and 6 may be relatively weaker in coupling strengths but theirweights can be relatively reduced. Thus, the structures of FIGS. 5 and 6are mainly suitable for popular vehicles or light-weight vehicles.

On the other hand, the tubular back beam assembly 10 for a vehicleaccording to the present invention may have a structure in which onemain back beam 11 and one support back beam 14 are coupled so that onlyone of upper and lower portions of the main back beam 11 is insertedinto the opening of the support back beam 14 as shown in FIG. 5, or astructure in which one main back beam 11 and two support back beams 14are coupled so that the support back beams 14 are disposed on and underthe main back beam 11 respectively, as shown in FIG. 6.

In comparison with the structure of FIG. 5, the structure of FIG. 6 maybe heavier, but its capability of protecting the vehicle and thepassenger is better.

Hereinafter, a method of manufacturing the tubular back beam assemblyaccording to the present invention will be described.

In a manufacturing method according to various embodiments of thepresent invention, a plurality of main back beams 11 are coupled to eachother in a stacked way such as those shown in FIGS. 3, 4, and 7. Themanufacturing method includes cold rolling and hot stamping a tubularcarbonous material 21 to form a main back beam 11 in which at least oneflat portion 11 a is provided in a longitudinal direction, and couplingthe main back beams 11 in a vertically stacked structure so that theflat portions 11 a are coupled in a surface contact fashion. Thereby,the tubular back beam assembly 10 is manufactured.

Here, when the tubular carbonous material 21 is cold-rolled, a thicknessof the material 21 is reduced by about 50%. Thus, the tubular back beamassembly can be reduced in weight.

In addition, when the material whose thickness is reduced by the coldrolling is subsequently subjected to the hot stamping, tensile strengthof the formed main back beam 11 is increased by about 30%.

In other words, the main back beam 11 formed by the cold rolling and thehot stamping is thinner and stronger than a back beam formed by generalextrusion or roll forming. Thus, the capability of protecting thevehicle body and the passenger can be further improved.

Here, the main back beam 11 is preferably formed to have a quadrangularcross section or substantially a quadrangular cross section in order tosecure rigidity. One will appreciate that other cross-sectionalgeometries may be used in accordance with the present invention. Theflat portions 11 a of the main back beams 11 which are coupled in asurface contact fashion by arc welding.

Arc welding has an advantage in that it has a shorter welding time thanspot welding which is typically used when the back beam assembly ismanufactured, and can improve productivity.

In a manufacturing method according to various other embodiments of thepresent invention, a main back beam 11 and a support back beam 14 arecoupled to each other in a stacked way such as those shown in FIGS. 5,6, and 8. The manufacturing method includes cold rolling and hotstamping a carbonous material 31 to form at least one support back beam14 having a C-shaped cross section in which one side thereof is openedin a longitudinal direction, cold rolling and hot stamping a tubularcarbonous material 21 to form a main back beam 11 having a quadrangularcross section, and coupling the support back beam 14 and the main backbeam 11 in a vertically stacked structure. Thereby, the tubular backbeam assembly 10 is manufactured.

Here, the carbonous material 31 used to form the support back beam 14 ispreferably a material having a plate shape rather than the tubularshape. However, the shape is not limited to the plate shape.

When the tubular back beam assembly 10 is manufactured, one portion ofthe main back beam 11 is inserted into an opening of the support backbeam 14, and then both ends of the support back beam 14 and anoverlapping portion of the main back beam 11 are coupled such as by arcwelding.

In addition, the tubular back beam assembly 10 may be manufactured sothat the one support back beam 14 and the one main back beam are coupledin a stacked way as shown in FIG. 5, or the support back beams 14 arecoupled on and under the main back beam 11 in a stacked way, as shown inFIG. 6.

As described above, the tubular back beam assembly 10 according tovarious embodiments of the present invention has a structure in whichthe plurality of main back beams 11 are coupled in a vertically stackedstructure with the flat portions coupled in a surface contact fashion,or the main back beam 11 and the support back beam 14 are directlycoupled in a vertically stacked way. Thereby, physical properties(coupling strength and bending rigidity based on the surface contactfashion of the coupling portions) of the tubular back beam assembly 10are remarkably increased. As a result, there is an advantage in thatsufficient collision strength can be secured, and the capability ofprotecting the vehicle and the passenger can be improved.

In addition, the tubular back beam assembly 10 according to the presentinvention is manufactured by cold rolling and hot stamping the materialof the back beam. Thus, there is an advantage in that the tubular backbeam assembly 10 can be reduced in weight, and be remarkably improved incoupling strength.

For convenience in explanation and accurate definition in the appendedclaims, the terms “upper” or “lower”, and etc. are used to describefeatures of the exemplary embodiments with reference to the positions ofsuch features as displayed in the figures.

The foregoing descriptions of specific exemplary embodiments of thepresent invention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteachings. The exemplary embodiments were chosen and described in orderto explain certain principles of the invention and their practicalapplication, to thereby enable others skilled in the art to make andutilize various exemplary embodiments of the present invention, as wellas various alternatives and modifications thereof. It is intended thatthe scope of the invention be defined by the Claims appended hereto andtheir equivalents.

What is claimed is:
 1. A tubular back beam assembly for a vehiclecomprising: a plurality of main back beams, each of which is formed in atubular shape and includes at least one flat portion, wherein theplurality of the main back beams are coupled to form a verticallystacked structure with the flat portions of adjacent main back beamscoupled in a surface contact fashion.
 2. The tubular back beam assemblyof claim 1, further comprising: a pair of crash boxes whose front endsare coupled to rear surfaces of the main back beams at both ends of themain back beams and whose rear ends are coupled to members of a vehiclebody, wherein vertical faces of the front ends of the crash boxes arecoupled to each of the plurality of the main back beams.
 3. The tubularback beam assembly of claim 2, further comprising: a towing hook, oneend of which is detachably coupled to at least one of the main backbeams to which the crash boxes are coupled.
 4. The tubular back beamassembly of claim 1, wherein one or each of the plurality of the mainback beams is formed to have substantially a quadrangular cross sectionto secure rigidity.
 5. The tubular back beam assembly of claim 1,wherein the flat portions of the adjacent main back beams are coupled toeach other by welding.
 6. The tubular back beam assembly of claim 1,further comprising: a support back beam which is formed to have aC-shaped cross section with an opening extended in a longitudinaldirection; and wherein the main back beam is formed in a tubular shapehaving substantially a quadrangular cross section and one portion ofwhich is inserted into the opening of the support back beam to close theopening of the support back beam and form a vertically stacked structurealong with the support back beam.
 7. The tubular back beam assembly ofclaim 6, wherein the main back beam and the support back beam arecoupled so that only one of an upper portion or a lower portion of themain back beam is inserted into the opening of the support back beam. 8.The tubular back beam assembly of claim 6, wherein the tubular back beamassembly includes a pair of the support back beams, one disposed on themain back beam and one disposed under the main back beam; and the mainback beam and the support back beams are coupled so that the upper andlower portions of the main back beam are inserted into the openings ofthe support back beams.
 9. A method of manufacturing a tubular back beamassembly for a vehicle, the method comprising: cold rolling and hotstamping a tubular carbonous material to form at least two main backbeams, each including at least one flat portion extended in alongitudinal direction; and coupling the at least two main back beams toform a vertically stacked structure with the flat portions of adjacentmain back beams coupled in a surface contact fashion.
 10. The method ofclaim 9, wherein one or each of the at least two main back beams isformed to have substantially a quadrangular cross section to securerigidity.
 11. The method of claim 9, wherein the flat portions of theadjacent tubular back beams are coupled in the surface contact fashionby arc welding.
 12. A method of manufacturing a tubular back beamassembly for a vehicle, the method comprising: cold rolling and hotstamping a carbonous material to form at least one support back beamhaving a C-shaped cross section with an opening extended in alongitudinal direction; cold rolling and hot stamping a tubularcarbonous material to form at least one main back beam havingsubstantially a quadrangular cross section; and coupling the at leastone support back beam and the at least one main back beam to form avertically stacked structure.
 13. The method of claim 12, wherein thecoupling of the support back beam and the main back beam includes:inserting one portion of the main back beam into the opening of thesupport back beam, and coupling both ends of the support back beam andan overlapping portion of the main back beam by arc welding.
 14. Themethod of claim 13, wherein the at least one support back beam and theat least one main back beam are coupled in a stacked way.
 15. The methodof claim 13, wherein the at least one support back beam includes twosupport back beams which are disposed on and under the main back beamand coupled with the main back beam in a stacked way.